Category Archives: ESP32

arduino, ESP32, Hardware, programming

Nodemcu ESP8266 Pinout, Specs, Versions with detailed board layout

Nodemcu ESP8266 Pinout, Specs, Versions with detailed board layout

Nodemcu Esp8266 Pinout, specs and detail board layout

NodeMCU esp8266 wifi module is an open-source, low-cost, low-power MCU(microcontroller unit) development board. It has 17 GPIO pins(11 are Digital I/O pins), out of which one pin is an analog pin, 4 pins support PWM, 2 pairs are for UART(UART0 and UART1), and supports 1x SPI and 1x I2C protocol.

NodeMCU ESP8266 has 128Kb of RAM, 4 MB of Flash memory, and a maximum clock speed of 160MHz(80 -160). The operating current is 80mA(average).

The ESP8266 Integrates an 802.11b/g/n HT40 Wi-Fi transceiver chip for WiFi connectivity and gives it the additional advantage of creating its network thus allowing other devices to connect directly to it.

Note: When ESP8266 was released, its open-source firmware was called Nodemcu by the developers. But now the term “Nodemcu” usually refers to the ESP8266 Wifi module.

Nodemcu versions or generations:

As of now, there are three official versions of the Nodemcu: Nodemcu Devkit 0.9 or Nodemcu V1, Nodemcu Devkit 1.0 or Nodemcu V2, and Lolin Nodemcu or Nodemcu V3.

Nodemcu generations or versions
Nodemcu generations or versions

Nodemcu Esp8266 packaging style

Two main packaging types of Nodemcu are available in the market: Amica and LoLin.

Amica Nodemcu package

The Amica Nodemcu has narrow pin spacing and measures 49mm x 26mm with a standard pin space of 0.1″ between pins and 0.9″ between rows.

Nodemcu-esp8266-board
Nodemcu esp8266 board in Amica package

LoLin nodemcu package

The Lolin Nodemcu has a wider pin spacing and larger board layout than the Amica package. It measures 58mm x 32mm with a pin spacing of 0.1″ between pins and 1.1″ between rows.

Lolin Nodemcu ESP8266 Board
LoLin Nodemcu ESP8266 Board

Note: The Amica NodeMCU is approximately 25% smaller in size than a closely compatible LoLin style NodeMCU.

Note: The LoLin board has 2 extra pins: VU and Ground pin. The VU pin is directly connected to the USB port power pin which can deliver 5V if the board is powered using a USB.

NodeMCU esp8266 wifi module is mostly used for IoT-based projects. By using NodeMCU ESP8266 Wifi Module, IoT applications become easier and cheaper.

Please note that the ESP8266 is a breadboard-friendly development board. And at its heart is a wifi module called ESP-12E. The ESP-12E is a tiny wifi module or the miniature version of ESP8266 that gives ESP8266 the functionality of Wireless communication. You can say, it is the brain of the ESP8266 Wifi module.

ESP8266 wifi module board layout

The Nodemcu wifi module comprises of ESP12E chip(the brain of the module), GPIO pins for easy interfacing, 3.3 Volt Voltage regulator, onboard LED, USB to serial converter IC, USB port, and more.

Nodemcu esp8266 board layout
Nodemcu esp8266 board layout

ESP8266-12E wifi chip with antenna

This esp8266-12E or simply esp-12E chip is a member of the esp-xx series. There are 15 modules ranging from esp01 to esp15. These are mostly used for IoT applications due to their small form factor and low price.

Processor: The latest ESP12E board integrates a Tensilica LX106 32-bit RISC processor, which achieves extra-low power consumption and reaches a maximum clock speed of 160 MHz.

Uploading a program in ESP-12E using the micro USB cable is difficult as it requires a separate 3.3 voltage regulator, reset button, some resistors, and a USB to TTL converter IC.

But the development board Nodemcu ESP8266 module has everything mentioned above, thus it is easy to program it from your laptop/PC. Nodemcu ESP8266 has an Esp12e chip, a USB port to upload programs, and for power supply. It also has a reset and boot button.

Hence the Nodemcu is a better choice over the esp12e chip as it is easy to use, is breadboard-friendly, and comes at the same price.

Voltage regulator AMS1117

The esp12e chip works on 3.3 Volts. But since a micro USB cable provides 5 Volts, the Nodemcu has an on-board 3.3 V voltage regulator which is AMS1117.

USB to TTL/serial converter

To program the board using a USB cable, the USB to TTL/UART converter IC is needed. Nodemcu ESP8266 has CP2102 USB to UART bridge controller IC (in SMD QFN-28 package). Some old ESP8266 boards use CH340G USB to TTL converter IC (in SMD SOP-16 package).

Usually, the Lolin Nodemcu has CP2102 and Amica Nodemcu has CH340G USB to TTL converter IC.

Flash button

The boot or flash button is used while uploading the program. If you hold it down and press the EN/RST, the ES8266 will restart in flashing/uploading mode

HiLetgo 1PC ESP8266 NodeMCU CP2102 ESP-12E...

HiLetgo 1PC ESP8266 NodeMCU CP2102 ESP-12E…

Nodemcu ESP8266 wifi module specifications

Let’s have a look at the specifications of NodeMCU.

Microcontroller ESP-8266 32-bit
NodeMCU Model Amica(official)
Clock Speed 80-160 MHz
USB to Serial CP2102
USB Connector Micro USB
Operating Voltage 3.3V
Input Voltage 4.5V-10V
Flash Memory/SRAM 4 MB / 128 KB
GPIO Pins 17
Digital I/O Pins 11
Analog In Pins 1
PWM Pins 4
ADC Range 0-3.3V
UART/SPI/I2C 2 / 1 / 1
WiFi Built-In 802.11 b/g/n
Temperature Range -40C – 125C

Nodemcu ESP8266 pinout

Nodemcu esp8266 pinout
Nodemcu esp8266 pinout

As shown in the above image, there is a total of 17 GPIO(General Purpose Input Output) pins. Out of which only 11 pins are best to use. These 11 pins are mentioned in the table given below. We can use those pins as an input or output.

Pin Name GPIO Input Output
D0 16 pull-up pull-up
D1 5 OK OK
D2 4 OK OK
D3 0 pull-up OK
D4 2 pull-up OK
D5 14 OK OK
D6 12 OK OK
D7 13 OK OK
D8 15 pull-down OK
RX 3 pull-up NO
TX 1 NO pull-up
A0 ADC0 Analog NO

Power pins

Vin: This pin can be used to power the esp8266 board. Up to 5V can be supplied to it. The Vin pin can be used to directly supply the Nodemcu esp8266 and its peripherals if you have a regulated 5V voltage source. This 5 volt is then converted to 3.3 volts using a voltage regulator as the esp12e chip requires 3.3V to operate.

Note: The Lolin ESP8266 module has one extra pin called VU. If the module is powered from a USB(5V), you can get 5V from the VU pin to power the external devices.

3.3 V: The board has three 3.3V pins. While the 3.3V pin is the output of a voltage regulator (CP2102), it can be used to power up the external components.

GND: There are a total of 4 such pins.

Note: All the GPIO pins of the ESP8266 are 3.3 V compatible(I/O) and are not 5V tolerant. Supplying 5 volts or more directly to any of the pins may damage the board.

ADC(Analog to digital) channel

ESP8266 has an inbuilt 10-bit ADC or analog-to-digital converter with only one ADC channel. In other words, the board has only one analog pin to read the analog voltage values from external devices like sensors and potentiometers.

This analog pin is marked as A0 on the board as given in the pinout diagram above.

UART (Universal Asynchronous Receiver-Transmitter) pins

The esp8266 board has 2 UART interfaces– RX0 and TX0 are UART0, RX2 and TX2 are UART1. The UART1 is used for uploading the firmware or program.

UART0 pins

  • U0 TXD (GPIO1)
  • U0 RXD (GPIO3)

UART1 pins

  • U1 TXD (GPIO15)
  • U1 RXD (GPIO13)

SPI pins

Unlike the three UART interfaces, the Esp8266 Nodemcu has only one set of SPI pins. The SPI protocol requires 4 pins: MOSI, MISO, SCLK, and CS.

  • GPIO 7: MISO
  • GPIO 8: MISO
  • GPIO 6: SCLK
  • GPIO 11: CS

I2C pins

The ESP8266 does not support any hardware I2C protocol, but it is possible to implement it in the programming part. So you may use any GPIO pins as I2C as long as you are aware of the I2C programming. Only two pins are required for I2C: SDA and SCLK.

Usually, the following GPIOs are used as I2C pins:

  • GPIO 4: SDA
  • GPIO 5: SCL

PWM pins

The board comes with 4 PWM-enabled pins. The PWM output can be used for driving digital motors and LEDs. PWM pins on the ESP8266 board are GPIO 4, GPIO 12, GPIO 14, and GPIO 15. OR digital pins D2, D5, D6, and D8.

EN or enable pin

EN stands for Enable, which enables the esp8266 chip i.e. ESP12E when pulled high. The chip works at minimum power when the EN pin is pulled low.

RST or reset Pin

This pin resets the board when pulled low. It works like the onboard reset button.

Wake pin(D0)

This pin is used to wake up the esp8266 chip from a deep sleep.

NOTE: EN, RST, and Wake pins are called the control pins of the ESP8266 board.

Nodemcu ESP8266 datasheet(ESP-12E):

To download the datasheet of this development board, click here.

Nodemcu dimensions

Amica nodemcu V2 dimensions:

The physical dimension of Amica or Nodemcu V2 is 4.8 X 2.6 in Centimeters.

Amica Nodemcu esp8266 dimensions
Amica Nodemcu esp8266 dimensions

LoLin nodemcu V3 dimensions:

The physical dimension of LoLin or Nodemcu V3 is 5.8 X 3.1 Centimeters.

Lolin Nodemcu ESP8266 dimensions
LoLin Nodemcu ESP8266 dimensions

FAQs

Why is ESP8266 used?

ESP8266 is used for its low-cost, integrated Wi-Fi capabilities, making it ideal for IoT projects and DIY electronics. Its small form factor, low power consumption, and ease of programming contribute to its popularity in applications like home automation, sensor networks, and remote monitoring.

Is NodeMCU and Arduino same?

No, NodeMCU and Arduino are not the same. NodeMCU is a development board based on the ESP8266 microcontroller, primarily used for IoT projects and Wi-Fi connectivity. Arduino is a popular open-source electronics platform based on various microcontrollers, offering a wide range of development boards for different applications.

What language is used for NodeMCU?

NodeMCU primarily uses Lua for programming, but C/C++ (via Arduino IDE) and MicroPython are also options.

Source: Nodemcu ESP8266 Pinout, Specs, Versions with detailed board layout

arduino, electronics, ESP32, iot

Duo series | Milk-V

Milk-V Duo is an ultra-compact embedded development platform based on the CV1800B chip. It can run Linux and RTOS, providing a reliable, low-cost, and high-performance platform for professionals, industrial ODMs, AIoT enthusiasts, DIY hobbyists, and creators.

The Milk-V Duo 256M is an upgraded version of Duo with a memory boost to 256M, catering to applications demanding larger memory capacities. It features the SG2002 computing series chip, elevating computational power to 1.0TOPS@INT8. It enables seamless switching between RISC-V/ARM architectures and supports simultaneous operation of dual systems. Additionally, it includes an array of rich GPIO interfaces such as SPI, UART, suitable for a wide range of hardware development in edge intelligent monitoring, including IP cameras, smart peephole locks, visual doorbells, and more.

Source: Duo series | Milk-V

arduino, ESP32, microcontrollers

ESP8266 – AT Command Reference · room-15

ESP8266 – AT Command Reference

ESP8266, in it’s default configuration, boots up into the serial modem mode. In this mode you can communicate with it using a set of AT commands.  AT commands that ESP8266 supports, explain what they do and how to use them.

Historically AT commands are based on the Hayes Command Set and these are no different.

AT Commands

Index of all known AT commands

Basic WiFI layer TCPIP Layer
AT AT+CWMODE AT+CIPSTATUS
AT+RST AT+CWJAP AT+CIPSTART
AT+GMR AT+CWLAP AT+CIPSEND
AT+GSLP AT+CWQAP AT+CIPCLOSE
ATE AT+CWSAP AT+CIFSR
AT+CWLIF AT+CIPMUX
AT+CWDHCP AT+CIPSERVER
AT+CIPSTAMAC AT+CIPMODE
AT+CIPAPMAC AT+CIPSTO
AT+CIPSTA AT+CIUPDATE
AT+CIPAP +IPD

Line termination

ESP8266 expects <CR><LF> or CarriageReturn and LineFeed at the end of each command, but just<CR> seems to work too.

Command variants

Each command can have up to 4 variants changing the function of it. You can chose between them by appending one of four possible values to the end of the root command itself. These four appendices can have the following values "",=<parameter|[parameters]>,"?",=?

Type Example Description
Test AT+CIPSTART=? Query the range of values (So far only AT+CWMODE=? uses it)
Query AT+CMD? Returns the current value of the parameter.
Set AT+CMD=Parameter Set the value of user-defined parameters in commands and run.
Execute AT+CMD Runs commands with no user-defined parameters.
Note:
  • Not all AT commands support all 4 variants.
  • [] = default value, not required or may not appear.
  • String values require double quotation marks, for example: AT+CWSAP="ESP756190","21030826",1,4.
  • Baud rate = 115200
  • AT instruction ends with “\r\n”

Commands

AT – Test AT startup

Variant Command Response Function
Execute AT OK Test if AT system works correctly

Back to Index

AT+RST – Restart module

Variant Command Response Function
Execute AT+RST OK Reset the module

ESP-01 Output after reset:

 ets Jan  8 2013,rst cause:4, boot mode:(3,7)

wdt reset
load 0x40100000, len 24444, room 16
tail 12
chksum 0xe0
ho 0 tail 12 room 4
load 0x3ffe8000, len 3168, room 12
tail 4
chksum 0x93
load 0x3ffe8c60, len 4956, room 4
tail 8
chksum 0xbd
csum 0xbd

ready

ESP-12 Output after reset:

\0x04B1\0x85 \0xff\0x13:'\0xe0;\0xcc;!G\0xfa\0x11\0xa9R\0xc6\0x83\0x01\0xd9\0x81
[Vendor:www.ai-thinker.com Version:0.9.2.4]

ready

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AT+GMR – View version info

Variant Command Response Function
Execute AT+GMR version, OK Print firmware version
Parameters:
  • version: firmware version number
ESP-01 output:
00160901
ESP-12 output:
0018000902-AI03

Back to Index

AT+GSLP – Enter deep-sleep mode

Variant Command Response Function
set AT+GSLP=time time OK Enter deep sleep mode for time milliseconds
parameters:
  • time: Time to sleep in milliseconds
Example：

AT+GSLP=1500

Note:

Hardware has to support deep-sleep wake up (Reset pin has to be High).

Back to Index

ATE – Enable / Disable echo

Variant Command Response Function
Execute ATE0 OK Disable echo (Doesn’t send back received command)
Execute ATE1 OK Enable echo (Sends back received command before response)
Note:

I haven’t had any luck with this command yet. Both ATE0 and ATE1 return no this fun.
ATE returns OK
This changed with ESP-12 where the command functions exactly as expected!

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AT+CWMODE – WIFI mode（station, AP, station + AP）

Variant Command Response Function
Test AT+CWMODE=? +CWMODE:(1-3) OK List valid modes
Query AT+CWMODE? +CWMODE:mode OK Query AP’s info which is connect by ESP8266.
Execute AT+CWMODE=mode OK Set AP’s info which will be connect by ESP8266.
Parameters:
  • mode： An integer designating the mode of operation either 1, 2, or 3.
    1 = Station mode (client)
    2 = AP mode (host)
    3 = AP + Station mode (Yes, ESP8266 has a dual mode!)
Notes:

ESP-12 came configured as host with ssid set to ESP_A0A3F2, no password, channel 1 You can use AT+CWSAP? to find the current settings.

Back to Index

AT+CWJAP – Connect to AP

Variant Command Response Function
Query AT+CWJAP? + CWJAP:ssid OK Prints the SSID of Access Point ESP8266 is connected to.
Execute AT+CWJAP=ssid,pwd OK Commands ESP8266 to connect a SSID with supplied password.
Parameters:
  • ssid：String, AP’s SSID
  • pwd：String, not longer than 64 characters
Example：
AT+CWJAP="my-test-wifi","1234test"
Example AT+CWJAP?：
+CWJAP:"my-test-wifi"

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AT+CWLAP – Lists available APs

Variant Command Response Function
Set AT+CWLAP=ssid,mac,ch +CWLAP:ecn,ssid,rssi,mac OK Search available APs with specific conditions.
Execute AT+CWLAP AT+CWLAP:ecn,ssid,rssi,mac OK Lists available Access Points.
Parameters:
  • ecn:
    • 0 = OPEN
    • 1 = WEP
    • 2 = WPA_PSK
    • 3 = WPA2_PSK
    • 4 = WPA_WPA2_PSK
  • ssid: String, SSID of AP
  • rssi: signal strength
  • mac: String, MAC address
Note:

On ESP-01 I have had no luck with the set version of this command (AT+CWLAP=...). If you know what it does please let me know.
On ESP-12, the Set version of the command allows to see if a certain SSID, with certain MAC on certain channel exists. If it doesit is returned as one line of the Execute version of this command.

Example AT+CWLAP:
+CWLAP:(3,"CVBJB",-71,"f8:e4:fb:5b:a9:5a",1)
+CWLAP:(3,"HT_00d02d638ac3",-90,"04:f0:21:0f:1f:61",1)
+CWLAP:(3,"CLDRM",-69,"22:c9:d0:1a:f6:54",1)
+CWLAP:(2,"AllSaints",-88,"c4:01:7c:3b:08:48",1)
+CWLAP:(0,"AllSaints-Guest",-83,"c4:01:7c:7b:08:48",1)
+CWLAP:(0,"AllSaints-Guest",-83,"c4:01:7c:7b:05:08",6)
+CWLAP:(4,"C7FU24",-27,"e8:94:f6:90:f9:d7",6)
+CWLAP:(2,"AllSaints",-82,"c4:01:7c:3b:05:08",6)
+CWLAP:(3,"QGJTL",-87,"f8:e4:fb:b5:6b:b4",6)
+CWLAP:(4,"50EFA8",-78,"74:44:01:50:ef:a7",6)
+CWLAP:(0,"optimumwifi",-78,"76:44:01:50:ef:a8",6)
+CWLAP:(3,"BHQH4",-95,"18:1b:eb:1a:af:5b",6)
+CWLAP:(3,"NETGEAR49",-86,"84:1b:5e:e0:28:03",7)
+CWLAP:(3,"ngHub_319332NW00047",-56,"20:e5:2a:79:b1:2f",11)
+CWLAP:(3,"BFZR4",-73,"18:1b:eb:1d:c3:91",11)
+CWLAP:(1,"5FFVL",-82,"00:26:b8:b5:c0:f2",11)
+CWLAP:(3,"59G6D",-77,"00:7f:28:6d:91:7b",11)
+CWLAP:(3,"N16FU",-53,"20:cf:30:ce:60:fe",11)
+CWLAP:(3,"ITS",-82,"90:72:40:21:5f:76",11)
+CWLAP:(3,"ITS",-79,"24:a2:e1:f0:04:e4",11)
Example AT+CWLAP="N16FU","20:cf:30:ce:60:fe",11:
+CWLAP:(3,"N16FU",-53,"20:cf:30:ce:60:fe",11)

Back to Index

AT+CWQAP – Disconnect from AP

Variant Command Response Function
Execute AT+CWQAP OK Disconnect ESP8266 from the AP is currently connected to.
Note:

After running this command, if you run AT+CWJAP? it still shows the AP you were connected to before. Back to Index

AT+CWSAP – Configuration of softAP mode

Variant Command Response Function
Query AT+CWSAP? +CWSAP:ssid,pwd,ch,ecn OK Query configuration of ESP8266 softAP mode.
Set AT+CWSAP=ssid,pwd,ch,ecn OK Set configuration of softAP mode.
Parameters:
  • ssid: String, ESP8266’s softAP SSID
  • pwd: String, Password, no longer than 64 characters
  • ch: channel id
  • ecn:
    • 0 = OPEN
    • 2 = WPA_PSK
    • 3 = WPA2_PSK
    • 4 = WPA_WPA2_PSK

Example
AT+CWSAP="esp_123","1234test",5,3
AT+CWSAP? => +CWSAP:"esp_123","1234test",5,3

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AT+CWLIF – List clients connected to ESP8266 softAP

Variant Command Response Function
Execute AT+CWLIF [ip,other] OK List information on of connected clients.
Parameters:

ip: IP address of a client connected to the ESP8266 softAP other: Other info, look at example. I don’t know what it means yet.

Example (ESP-01):
AT+CWLIF

192.168.4.100,3fff50b4:3fff50ba:3fff50c0:3fff50c6:3fff50cc:3fff50d2

OK
Example (ESP-12):
AT+CWLIF

192.168.4.100,c0:ee:fb:25:33:ec

OK

I ran the command after connecting to the ESP8266 with my cellphone.

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AT+CWDHCP – Enable/Disable DHCP

Variant Command Response Function
Set AT+CWDHCP=mode,en OK Enable or disable DHCP for selected mode
Parameters:
  • mode:
    • 0 : set ESP8266 as a softAP
    • 1 : set ESP8266 as a station
    • 2 : set both ESP8266 to both softAP and a station
  • en:
    • 0 : Enable DHCP
    • 1 : Disable DHCP
Note:

This command doesn’t seem to work on firmware 00160901 (ESP-01) nor 0018000902-AI03 (ESP-12).

Back to Index

AT+CIPSTAMAC – Set MAC address of ESP8266 station

Variant Command Response Function
Query AT+CIPSTAMAC? +CIPSTAMAC:mac OK Print current MAC ESP8266’s address.
Execute AT+CIPSTAMAC=mac OK Set ESP8266’s MAC address.
Parameters:
  • mac： String, MAC address of the ESP8266 station.
Example:

AT+CIPSTAMAC="18:aa:35:97:d4:7b"

Note:

This command doesn’t seem to work on firmware 00160901

Back to Index

AT+CIPAPMAC – Set MAC address of ESP8266 softAP

Variant Command Response Function
Query AT+CIPAPMAC? +CIPAPMAC:mac OK Get MAC address of ESP8266 softAP.
Execute AT+CIPAPMAC=mac OK Set mac of ESP8266 softAP.
Parameters:
  • mac： String, MAC address of the ESP8266 softAP.
Example:

AT+CIPAPMAC=”2c:aa:35:97:d4:7b”

Note:

This command doesn’t seem to work on firmware 00160901

Back to Index

AT+CIPSTA – Set IP address of ESP8266 station

Variant Command Response Function
Query AT+CIPSTA? +CIPSTA:ip OK Get IP address of ESP8266 station.
Execute AT+CIPSTA=ip OK Set ip addr of ESP8266 station.
Parameters:
  • ip： String, ip address of the ESP8266 station.
Example:

AT+CIPSTA=”192.168.101.108”

Note:

This command doesn’t seem to work on firmware 00160901

Back to Index

AT+CIPAP – Set ip address of ESP8266 softAP

Variant Command Response Function
Query AT+CIPAP? +CIPAP:ip OK Get ip address of ESP8266 softAP.
Execute AT+CIPAP=ip OK Set ip addr of ESP8266 softAP.
Parameters:
  • ip： String, ip address of ESP8266 softAP.
Example:
AT+CIPAP="192.168.5.1"
Note:

This command doesn’t seem to work on firmware 00160901

Back to Index

AT+CIPSTATUS – Information about connection

Variant Command Response Function
Test AT+CIPSTATUS=? OK
Execute AT+CIPSTATUS STATUS:status +CIPSTATUS:id,type,addr,port,tetype OK Get information about connection.
Parameters:
  • status：
    • 2: Got IP
    • 3: Connected
    • 4: Disconnected
  • id： id of the connection (0~4), for multi-connect
  • type： String, “TCP” or “UDP”
  • addr： String, IP address.
  • port： port number
  • tetype：
    • 0 = ESP8266 runs as a client
    • 1 = ESP8266 runs as a server
Note:

On ESP-01 this command returns STATUS:1 instead (no extra info, but status changes) On 0018000902-AI03 this command returns STATUS:2 instead (no extra info, but status changes)

Back to Index

AT+CIPSTART – Establish TCP connection or register UDP port and start a connection

Variant Command Response Function
Set AT+CIPSTART=type,addr,port OK Start a connection as client. (Single connection mode)
Set AT+CIPSTART=id,type,addr,port OK Start a connection as client. (Multiple connection mode)
Test AT+CIPSTART=? [+CIPSTART:(id)(“type”),(“ip address”),(port)] OK List possible command variations)
Parameters:
  • id: 0-4, id of connection
  • type: String, “TCP” or “UDP”
  • addr: String, remote IP
  • port: String, remote port

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AT+CIPSEND – Send data

Variant Command Response Function
Test AT+CIPSEND=? OK
Set AT+CIPSEND=length SEND OK Set length of the data that will be sent. For normal send (single connection).
Set AT+CIPSEND=id,length SEND OK Set length of the data that will be sent. For normal send (multiple connection).
Execute AT+CIPSEND Send data. For unvarnished transmission mode.

Normal Mode

Parameters:
  • id: ID no. of transmit connection
  • length: data length, MAX 2048 bytes

Unvarnished Transmission Mode

Wrap return “>” after execute command. Enters unvarnished transmission, 20ms interval between each packet, maximum 2048 bytes per packet. When single packet containing “+++” is received, it returns to command mode.

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AT+CIPCLOSE – Close TCP or UDP connection

Variant Command Response Function
Test AT+CIPCLOSE=? OK
Set AT+CIPCLOSE=id OK Close TCP or UDP connection.For multiply connection mode
Execute AT+CIPCLOSE OK Close TCP or UDP connection.For single connection mode
Parameters:
  • id： ID no. of connection to close, when id=5, all connections will be closed.
Note:

In server mode, id = 5 has no effect!

Back to Index

AT+CIFSR – Get local IP address

Variant Command Response Function
Test AT+CIFSR=? OK
Execute AT+CIFSR +CIFSR:ip OK Get local IP address.
Parameters:
  • ip: IP address of the ESP8266 as an client.
Example AT+CIFSR:
10.101.10.134

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AT+CIPMUX – Enable multiple connections or not

Variant Command Response Function
Set AT+CIPMUX=mode OK Enable / disable multiplex mode (up to 4 conenctions)
Query AT+CIPMUX? +CIPMUX:mode OK Print current multiplex mode.
Parameters:
  • mode:
    • 0: Single connection
    • 1: Multiple connections (MAX 4)
NOTE:

This mode can only be changed after all connections are disconnected. If server is started, reboot is required.

Back to Index

AT+CIPSERVER – Configure as server

Variant Command Response Function
Set AT+CIPSERVER=mode[,port] OK Configure ESP8266 as server
Parameters:
  • mode:
  • 0: Delete server (need to follow by restart)
  • 1: Create server
  • port: port number, default is 333
NOTE:
  1. Server can only be created when AT+CIPMUX=1
  2. Server monitor will automatically be created when Server is created.
  3. When a client is connected to the server, it will take up one connection，be gave an id.

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AT+CIPMODE – Set transfer mode

Variant Command Response Function
Query AT+CIPMODE? +CIPMODE:mode OK Set transfer mode,normal or transparent transmission.
Set AT+CIPMODE=mode OK Set transfer mode,normal or transparent transmission.
Parameters:
  • mode:
  • 0: normal mode
  • 1: unvarnished transmission mode

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AT+CIPSTO – Set server timeout

Variant Command Response Function
Query AT+CIPSTO? +CIPSTO:time Query server timeout.
Set AT+CIPSTO=time OK Set server timeout.
Parameters:
  • time: server timeout, range 0~7200 seconds

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AT+CIUPDATE – update through network

!!! Don’t run this unless you know what you’re doing !!!

!!! It will likely brick your device !!!

Attempts to self-update from the internet.

Variant Command Response Function
Execute AT+CIUPDATE +CIPUPDATE:n OK Start update through network
Parameters:

–n:

  • 1: found server
  • 2: connect server
  • 3: got edition
  • 4: start update
Example:
AT+CIUPDATE

+CIUPDATE: 1
+CIUPDATE: 2
+CIUPDATE: 3
+CIUPDATE: 4

\0x02\0x8cl\0x8el\0x8e\0x1cp\0x0c\0x8c\0xf2nn\0xee\0x00l\0x8c\0x8el`
\0x02\0x90\0x12\0x12nnl\0x8cl`\0x02\0x0e\0x02nr\0x8e\0x92\0x92n\0x0c\0x0c
\0x02\0x8c\0x92`\0x02`
\0xf2n\0x0c\0x0c\0x0c\0x9e\0xe0b\0x82nl\0x8c\0x0c\0x8c
\0xf2nn\0xee\0x00\0x0c\0x8e\0x0elp\0xf2n\0xe0\0x10\0x02\0x0c
\0x0cr\0x8c\0x9c\0x9c\0xe2\0xe0\0x0c\0x0c\0x0c
\0x0cb\0x0cn\0xe2|\0x02\0xec\0xecl\0x8c\0x0cb\0x8c\0xf2nn
...forever

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+IPD – Receive network data

Variant Command Response Function
Execute +IPD,len:data Receive network data from single connection.
Execute +IPD,id,len:data Receive network data from multiple connection.
Parameters:
  • id: id no. of connection
  • len: data length
  • data: data received
Note:

I have had no luck with this command so far.

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Sources

esp8266 GitHub Wiki

Source: ESP8266 – AT Command Reference · room-15